John Curl's Blowtorch preamplifier part II

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#34,244
...and here are (self-censored) who claim to be annoyed by the 7th or 9th
harmonic at > -120 dB.
120 dB is the attenuation of a radio signal from here to the moon, to put
it in perspective. Or a jet engine at 30m distance to hearing threshold.


I don't recall anyone saying that they were annoyed by the 7th harmonic at -120db.
Can you give the reference link?
I do recall 7th harmonic being used as a guideline for measurement of quality.
 
#34,245
So do you put that brick wall filter before the TownShend tweeter to remove the upper frequencies so you don't have to hear that objectionable high frequency response?! Just goes to show you how opposing the theories are and what can be done. But I would sure like to know where the 24Khz and above material is supposed to be sourced from? Seems we have a quandary here, those who want upper end extension and those who profess that anything over 16Khz is just noise..... I'll stick with my thoughts that the experimenters have used devices that were just incapable of producing the upper frequencies without unwanted resonant breakup noise and distortion.
 
#34,246
Sy,
I just get peeved when so many knocked US based engineers as inferior. If that was the case why do so many come here to get educated. Our problem is we teach some of the best engineers and then tell them they have to go home now. Stupidist immigration policy if I ever saw one.
 
#34,248
john curl said:
Jack Bybee is just fine. He has received a prototype of our latest switching power supply, high feedback power amplifier, and is very happy with it. This is the one we have worked on for years, now.
Last night I contacted him that the BBC channel was showing a new Bentley that goes as fast as his Bentley (205 mph, tested) and the Top Gear guys put it into a rally, which was really fun to watch. Jack and I discussed it, after the rally was run. Jack told me that his Bentley has even more HP than the new Bentley. One of his old sidelines.
Click to expand...

Thanks for the update! 😉
 
#34,252
They're not. I've never done physiology (well there was a year in a lab at Johns Hopkins, but that was a long time ago and I was just a dumb technician). I never cut anyone's tongue out or their nose off for physical study, though I was tempted from time to time; our subjects just had to sniff and taste things to generate data similar to that shown in the linked article.
 
#34,257
scott wurcer said:
Don't you know the most important property of the content beyond 20kHz is to enhance the bass. Jeesh! 😛
Click to expand...
About my super tweeter's joke, i noticed in reviews that they all remark an improvement in basses. It is the same thing i remarked, when i changed an amp from voltage to current feedback with improved slewrate.
As it it not supposed to be so, in common audiophile believes, i suppose that it is something really experienced. May-be it is amelioration of the acoustic slew rate during transients ?
If i had enough money, i would like to try, just to be sure that it is pure bul*sh*t.
May-be it is an acoustic phase question, as well, or a group delay one ? it would be interesting to explore.
 
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#34,259
Since we are so ot here let me ask a question. Can somebody explain to me in plain English how dither, adding noise to a signal lowers the noise floor when reducing the bit rate? I have read some of the information that George has presented and am having a time of understanding the principal here. A serious question as it seems so important to using some of the digital volume controls and other things in the digital world.
 
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